1. Field of the Invention
This invention relates to the field of data protection, and in particular to protecting data from illicit copying from a remote location.
2. Description of Related Art
The protection of data is becoming an increasingly important area of security. In many situations,the authority to copy or otherwise process information is verified via a time-consuming process. For example, copy-protected material may contain watermarks or other encodings which identify the material as being copy-protected, and also contains other encodings which identify whether this particular copy of the material is an authorized copy, and whether it can be copied again. For example, an authorized copy of content material may contain a robust watermark and a fragile watermark. The robust watermark is intended to be irremovable from the content material without causing damage to the content material. The fragile watermark is intended to be damaged when the content material is illicitly copied. For example, common fragile watermarks are damaged if the content material is compressed or otherwise altered. In this manner, content material that is compressed in order to be efficiently communicated via the Internet will be received with a robust watermark and a damaged fragile watermark. A content-processing device that is configured to enforce copy protection rights in this example will be configured to detect the presence of a robust watermark, and prevent the processing of the content material containing this robust watermark unless the fragile watermark is also present. The time required to verify the presence of a robust and a fragile watermark, however, may be substantial. Other verification schemes may include accessing a remote source to verify a user identification or user authorization, and the transmission time delay may also be substantial. Still other verification schemes, discussed further below, may induce an even longer latency between when the content material is presented for processing and when the content material is verified as being authorized for processing.
In most consumer applications, the consumer expects a relatively immediate response to commands. For example, when a user presses “play” on a CD player, the user expects music to be rendered within a few seconds. If the user has an authorized copy of copy protected material, the user will expect the same relatively immediate response to commands when requesting access to this material. A security system that imposes a noticeable delay before responding to the user's commands for access to authorized content material will not be well received by consumers. In like manner, a security system that allows a substantial portion of unauthorized content material to be processed while the user's authorization is being verified, will not be well received by the providers of protected content material.